Condensed Consolidating Information (Income Statement) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues
Rental income									$ 1,593,598	$ 1,476,176	$ 1,346,046
Resident fees and services									1,843,232	1,847,306	1,811,255
Office building and other services revenue									13,677	21,070	41,492
Income from loans and investments									117,608	98,094	86,553
Equity earnings in affiliates									0	0	0
Interest and other income									6,034	876	1,052
Total revenues	$ 895,288	$ 899,928	$ 895,490	$ 883,443	$ 875,713	$ 867,116	$ 848,404	$ 852,289	3,574,149	3,443,522	3,286,398
Expenses
Interest									448,196	419,740	367,114
Depreciation and amortization									887,948	898,924	894,057
Property-level operating expenses									1,483,072	1,434,762	1,383,640
Office building services costs									3,391	7,311	26,565
General, administrative and professional fees									135,490	126,875	128,035
Loss on extinguishment of debt, net									754	2,779	14,411
Merger-related expenses and deal costs									10,535	24,635	102,944
Other									20,052	9,988	17,957
Total expenses									2,989,438	2,925,014	2,934,723
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests									584,711	518,508	351,675
Income (loss) from unconsolidated entities									(561)	4,358	(1,420)
Income tax benefit									59,799	31,343	39,284
Income from continuing operations	178,835	156,930	152,272	155,912	142,575	150,446	137,849	123,339	643,949	554,209	389,539
Discontinued operations	(15)	(19)	(23)	(53)	(167)	(118)	(148)	(489)	(110)	(922)	11,103
Gain on real estate dispositions	214,985	458,280	719	43,289	66,424	(144)	5,739	26,184	717,273	98,203	18,580
Net income	393,805	615,191	152,968	199,148	208,832	150,184	143,440	149,034	1,361,112	651,490	419,222
Net (loss) income attributable to noncontrolling interest, net of tax									4,642	2,259	1,379
Net income attributable to common stockholders	$ 392,554	$ 613,958	$ 151,831	$ 198,127	$ 207,637	$ 149,452	$ 143,162	$ 148,980	1,356,470	649,231	417,843
Consolidated Elimination
Revenues
Rental income									0	0	0
Resident fees and services									0	0	0
Office building and other services revenue									0	0	0
Income from loans and investments									0	0	0
Equity earnings in affiliates									(487,242)	(499,292)	(457,564)
Interest and other income									0	0	0
Total revenues									(487,242)	(499,292)	(457,564)
Expenses
Interest									0	0	0
Depreciation and amortization									0	0	0
Property-level operating expenses									0	0	0
Office building services costs									0	0	0
General, administrative and professional fees									0	0	0
Loss on extinguishment of debt, net									0	0	0
Merger-related expenses and deal costs									0	0	0
Other									0	0	0
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests									(487,242)	(499,292)	(457,564)
Income (loss) from unconsolidated entities									0	0	0
Income tax benefit									0	0	0
Income from continuing operations									(487,242)	(499,292)	(457,564)
Discontinued operations									0	0	0
Gain on real estate dispositions									0	0	0
Net income									(487,242)	(499,292)	(457,564)
Net (loss) income attributable to noncontrolling interest, net of tax									0	0	0
Net income attributable to common stockholders									(487,242)	(499,292)	(457,564)
Ventas, Inc.
Revenues
Rental income									2,383	2,670	3,663
Resident fees and services									0	0	0
Office building and other services revenue									0	1,605	895
Income from loans and investments									1,236	341	8,605
Equity earnings in affiliates									488,862	500,515	458,213
Interest and other income									5,388	666	495
Total revenues									497,869	505,797	471,871
Expenses
Interest									(101,222)	(46,650)	(38,393)
Depreciation and amortization									5,483	8,968	5,443
Property-level operating expenses									0	0	0
Office building services costs									0	0	0
General, administrative and professional fees									2,056	509	(321)
Loss on extinguishment of debt, net									0	0	0
Merger-related expenses and deal costs									9,797	23,068	98,644
Other									2,247	(705)	(358)
Total expenses									(81,639)	(14,810)	65,015
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests									579,508	520,607	406,856
Income (loss) from unconsolidated entities									0	0	0
Income tax benefit									59,799	31,343	39,284
Income from continuing operations									639,307	551,950	446,140
Discontinued operations									(110)	(922)	(46,877)
Gain on real estate dispositions									717,273	98,203	18,580
Net income									1,356,470	649,231	417,843
Net (loss) income attributable to noncontrolling interest, net of tax									0	0	0
Net income attributable to common stockholders									1,356,470	649,231	417,843
Ventas Realty
Revenues
Rental income									178,165	196,991	198,017
Resident fees and services									0	0	0
Office building and other services revenue									0	0	0
Income from loans and investments									0	0	534
Equity earnings in affiliates									0	0	0
Interest and other income									0	0
Interest and other income											(6)
Total revenues									178,165	196,991	198,545
Expenses
Interest									319,630	281,458	257,503
Depreciation and amortization									7,510	18,297	14,679
Property-level operating expenses									329	317	367
Office building services costs									0	0	0
General, administrative and professional fees									16,976	18,320	20,777
Loss on extinguishment of debt, net									943	2,770	4,523
Merger-related expenses and deal costs									0	0	75
Other									1	41	45
Total expenses									345,389	321,203	297,969
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests									(167,224)	(124,212)	(99,424)
Income (loss) from unconsolidated entities									5,306	1,840	(183)
Income tax benefit									0	0	0
Income from continuing operations									(161,918)	(122,372)	(99,607)
Discontinued operations									0	0	34,748
Gain on real estate dispositions									0	0	0
Net income									(161,918)	(122,372)	(64,859)
Net (loss) income attributable to noncontrolling interest, net of tax									0	0	0
Net income attributable to common stockholders									(161,918)	(122,372)	(64,859)
Ventas Subsidiaries
Revenues
Rental income									1,413,050	1,276,515	1,144,366
Resident fees and services									1,843,232	1,847,306	1,811,255
Office building and other services revenue									13,677	19,465	40,597
Income from loans and investments									116,372	97,753	77,414
Equity earnings in affiliates									(1,620)	(1,223)	(649)
Interest and other income									646	210	563
Total revenues									3,385,357	3,240,026	3,073,546
Expenses
Interest									229,788	184,932	148,004
Depreciation and amortization									874,955	871,659	873,935
Property-level operating expenses									1,482,743	1,434,445	1,383,273
Office building services costs									3,391	7,311	26,565
General, administrative and professional fees									116,458	108,046	107,579
Loss on extinguishment of debt, net									(189)	9	9,888
Merger-related expenses and deal costs									738	1,567	4,225
Other									17,804	10,652	18,270
Total expenses									2,725,688	2,618,621	2,571,739
Income before unconsolidated entities, income taxes, discontinued operations, real estate dispositions and noncontrolling interests									659,669	621,405	501,807
Income (loss) from unconsolidated entities									(5,867)	2,518	(1,237)
Income tax benefit									0	0	0
Income from continuing operations									653,802	623,923	500,570
Discontinued operations									0	0	23,232
Gain on real estate dispositions									0	0	0
Net income									653,802	623,923	523,802
Net (loss) income attributable to noncontrolling interest, net of tax									4,642	2,259	1,379
Net income attributable to common stockholders									$ 649,160	$ 621,664	$ 522,423